Usage:
Ancell Group (IL,IN,IA,WI)
Subunits:
(alphabetical): Dutchtown Limestone (IL,IN), Glenwood Formation (IL,IA,WI), Joachim Dolomite (IL,IN), St. Peter Sandstone (IL,IN,IA,WI).
Geologic age:
Middle to Late Ordovician (Whiterockian to Mohawkian)
Type section, locality, area and/or origin of name:
Type section (composite): several sections in the bluffs between Dutchtown and Rock Levee, north of Ancell, Cape Girardeau Co., MO (Templeton and Willman, 1963).
AAPG geologic province:
Illinois basin
Iowa shelf
Upper Mississippi embayment
Wisconsin arch
For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.
Asterisk (*) indicates published by U.S. Geological Survey authors.
"No current usage" (†) implies that a name has been abandoned or has fallen into disuse. Former usage and, if known, replacement name given in parentheses ( ).
Slash (/) indicates name conflicts with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005, 2021). May be explained within brackets ([ ]).